1. Field of the Invention
The present invention relates to a lens unit for a camera. More concretely, the present invention relates to the lens unit in which a lens can be moved to its optical axis direction in order to switch between a standard photographing position and a macro photographing position.
2. Description of the Related Art
Conventionally, in lens units to be used for cameras or the like, all or some of a plurality of lenses can be moved manually or automatically to an optical axis direction in order to adjust focus or the like. Cameras in which an adjustment is made manually are generally provided with a ring-shaped focus ring on an outer periphery of a lens frame for holding the lens, and the focus ring is rotated to adjust the focus. The rotation of the focus ring is converted into a movement of the lens frame to the optical axis direction by a mechanism such as a screw or a cam, so that the lens is moved to the optical axis direction (for example, Japanese Utility Model Application Laid-Open No. (5-45619)).
The lens units to be used for cameras which are capable of switching between the standard photographing mode and the macro photographing mode generally have a lever or the like for switching an arrangement of the lens frame between the standard photographing position and the macro photographing position. When the lever is operated, the lens frame advances or retreats to the optical axis direction by a predetermined distance via the mechanism such as a screw or a cam (for example, Japanese Patent Application Laid-Open No. 2003-337279). In such lens units, a ring-shaped member having a cam portion or a screw portion is provided to a periphery of the lens frame, and the ring-shaped member is engaged with the cam portion or the screw portion provided to the outer periphery of the lens frame. The ring-shaped member is rotated by a lever or the like, so that the lens position is adjusted. A spring or the like, which always biases the lens frame to a predetermined direction, is provided to the periphery of the lens frame.
In the conventional lens units, however, the ring-shaped member which has the cam portion and the screw portion for switching the position of the lens frame is provided over the entire periphery of the lens frame. Further, a coil spring or the like which is wound around the outer periphery of the lens frame is occasionally provided in order to bias the lens frame to a predetermined direction. For this reason, a space where the members are arranged should be provided to the periphery of the lens frame, and thus a projecting area in the optical axis direction of the entire lens unit tend to become large. Particularly lens units for miniature cameras to be mounted on mobile devices or the like are required to be further miniaturized.